1. Field of the Invention
This invention relates to a seal assembly for providing sealing engagement between a vessel and a rotatable shaft extending through a wall of the vessel.
2. Description of Prior Art
In material processing equipment it is common that a rotatable shaft is positioned through a wall of a vessel containing material. The interface between the rotatable shaft and the vessel is often the source of leaks of the material as the rotatable shaft rotates. Mechanical, safety and efficiency problems may occur if the material contaminates the processing equipment, the material is hazardous or the material is expensive.
Stuffing boxes were often used in the prior art in an attempt to seal the area between the rotatable shaft and the vessel. A stuffing box comprises a box that is filled with dense packing or stuffing attached to the vessel around the interface between the vessel and the rotatable shaft. Such stuffing boxes are often ineffective after extended periods because the packing or stuffing begins to wear away around the rotatable shaft.
Other prior art sealing apparatuses, such as Escue, U.S. Pat. No. 4,575,098, use a series of rotatable components attached with respect to the shaft and the vessel. The Escue patent teaches an undersized collar attached to the shaft which rotates around an insert and a faceplate. The seal apparatus taught by the Escue patent involves many rotating components which may result in wear of several different components. Such wear results in frequent replacement of various components.